Drive with caution — fix soon.
This code means the fuel composition sensor's readings are outside the normal range or not changing as expected, so the computer can't trust the ethanol reading. It's often caused by a failing sensor, wiring issues, contaminated fuel, or a sensor that has drifted out of calibration. It's generally a sensor-level fault and fixable once the sensor and its circuit are tested.
$120 – $500
Varies by vehicle and root cause.
Usually yes. The car typically still drives, but the fuel mixture may be slightly off, so it's best to have it diagnosed within a week or two to avoid rough running or wasted fuel.
Fixing wiring or a connector may be around $120, while replacing the fuel composition sensor with parts and labor can run up to about $500.
It's moderate. It rarely causes a breakdown, but inaccurate fuel readings can hurt drivability and economy, so it's worth addressing before symptoms get worse.
The sensor may be aging and drifting, have a wiring fault, or be confused by contaminated fuel. A technician can compare its readings against known good values to confirm.